1. Field of the Invention
The present invention relates to an apparatus and method for decreasing drag force by controlling turbulent flow on a hull surface of a ship, and more particularly, to an apparatus and method for decreasing drag force by controlling turbulent flow on the hull surface by performing suction and ejection of fluid flowing around the hull surface to decrease friction resistance thereon.
2. Description of the Related Art
When a ship is out at sea, friction resistance is caused on a hull surface of the ship due to vortex flow on the hull surface. This friction resistance generally takes a significant portion of the total resistive drag force which a ship is subject to at sea. For example, in case of an oil carrier, the friction resistance takes about 80% of the total drag force.
There has been a development in techniques of decreasing the friction resistance occurring on a hull surface of a ship. A widely used method is ejecting air or syrupy liquid from a bow side of a ship. However, there have been difficulties in decreasing the friction resistance in the conventional methods and apparatuses.
The present invention provides an apparatus and method for decreasing drag force based on a control of turbulent flow on a hull surface of a ship, in which fluid flowing around the hull surface of a ship is sucked and ejected, and an ejection angle with respect to the hull surface is adjusted, to thereby control the turbulent flow on the hull surface.
The present invention also provides an apparatus and method for decreasing drag force by controlling turbulent flow on a hull surface of a ship, in which suction and ejection of fluid flowing around the hull surface extended from the inside of the hull of a ship is repeatedly performed by installing a pipe housing including a flexible air pipe or plates along the hull surface of a ship, to thereby control a turbulent flow boundary layer on the hull surface.
The present invention further provides an apparatus and method for decreasing drag force by controlling turbulent flow on a hull surface of a ship, in which the turbulent flow is locally controlled by installing an apparatus having a flexible air pipe or plates at a bow or stem of the ship.
In an exemplary embodiment of the present invention, there is provided a method for decreasing drag force by controlling turbulent flow in a hull surface of a ship in which fluid flowing around the hull surface of a ship is sucked and ejected to vary turbulent field of the fluid flow, and friction resistance is decreased by controlling an ejection angle with respect to the hull surface of a ship.
In another exemplary embodiment of the present invention, there is provided an apparatus for decreasing drag force by controlling turbulent flow on a hull surface of a ship, which includes a pipe housing which is installed on the hull surface of a ship and includes a plurality of slits, a flexible air pipe which is installed in the interior of the pipe housing and performs a contracting and/or expanding operation in association with an air pumping operation, and a pump which is connected to the flexible air pipe, for sucking and discharging the air.
In another exemplary embodiment of the present invention, there is provided an apparatus for decreasing drag force by controlling turbulent flow on a hull surface of a ship, which includes a pipe housing which is installed on the hull surface of a ship and includes a plurality of slits, plates which are installed in the pipe housing and positioned in the upper and lower portions of the respective slits, a first rod connected with the plates positioned in the upper portions of the respective slits, a second rod connected with the plates positioned in the lower portions of the respective slits, and a motor which is installed in the interior of the ship and connected to the first and second rods to drive the first and second rods.